Truck mounted tanks are commonly used for transport and delivery of hazardous materials such as propylene, butane, gasoline, liquid propane gas (LPG), anhydrous ammonia (NH.sub.3) and diesel fuel. The truck may take the form of what is known as a "bobtail" truck where the tank is coupled directly to the truck frame, or a tractor-trailer combination where the tank is mounted directly to the trailer frame. In either case, a first inlet valve is provided for filling the tank from a bulk plant or other vehicle, and a second outlet valve allows for discharging the fluid from the vehicle storage tank.
All bobtail trucks, tractor-trailer combinations and bulk plants that handle any of the aforementioned hazardous materials are required by state and federal law to include a safety release system. The safety release system typically includes a manually operated release handle mounted to an aft portion of the cab in the case of a bobtail truck and to a forward portion of the trailer adjacent the cab in a tractor-trailer combination. The release handle is coupled by means of either cables or air-activated RAMs to storage tank valves on the vehicle to close the tank outlets in a hazardous situation such as a spill or a fire. In order for the safety system to be actuated, the operator must be within arm's length of the safety release handle. However, when dealing with highly flammable materials, which may also be highly contaminating and corrosive and which also frequently are maintained under high pressure within the storage tank, operator access to the safety release handle may be physically impossible in most hazardous situations typically encountered. Indeed, in the case of a fire or spill, the operator may be seriously injured or killed even attempting to reach the safety release handle. Moreover, even if the vehicle operator is able to close the storage tank valves, he must then enter the vehicle cab to turn the vehicle's engine off to prevent the possibility of an explosion or fire caused by the vehicle's ignition system. The performance of one or both of these actions requires precious seconds which may mean the difference between life and death, between total destruction and a minor, contained accident.
In off-loading the vehicle's storage tank, the operator checks the number of gallons discharged from the tank as indicated on a vehicle-mounted digital readout with a percent fill gauge on the customer's storage tank to avoid an overfill situation and material leakage in the event of indicator or flow sensor malfunction. This requires the operator to leave the vehicle for what frequently is an extended period. The distance from the delivery truck to the stationary storage tank may in some cases be considerable, making the vehicle's safety release system for all practical purposes inaccessible in the event of an accident. At pressures of 250 pounds per square inch, a large quantity of hazardous material may be discharged in a very short period of time.
The present invention addresses the aforementioned limitations of the prior art by greatly reducing the possibility of injury and property damage when a break occurs in plumbing, hoses, etc., of a vehicle storage tank containing a hazardous material resulting in a spill. An operator actuated, remotely located controller allows an operator to immediately close all tank valves upon detection of a potentially dangerous situation. The remote controller also allows for immediate shutdown of the vehicle's engine in eliminating it as a source of combustion ignition and terminating the operation of the vehicle's discharge pump.